1. Field of Invention
The present invention relates to a display device structure and a manufacturing method thereof. More particularly, the present invention relates to an electrophoretic display device and manufacturing method thereof.
2. Description of Related Art
The electrophoretic display device, also known as the electronic paper display device (Electronic Paper Display; EPD), has a thin and flexible outlook and the low power consumption. The electrophoretic display device provides the users the book reading like feeling. The electrophoretic display device can update the information via the electronic ink (E-ink) technology as well as the charges. The E-Ink technology is applied to the electrophoretic display device without the front light module or the back light module and is viewable even under the direct sunlight. An image on the screen of the electrophoretic display device can be retained even when all power sources are removed.
The electronic ink is mainly composed of millions of tiny particles, and the size of particles is roughly equal to the size of the human hair. In general, each tiny particle contains the white particles with the positive charges and the black particles with the negative charges, in which these particles suspend in the serum. When the electric field is applied, the white particles with the positive charges move to the end and appear white, while the black particles with the negative charges move to the other end and appear black.
During the manufacturing process of the electronic ink display, the electrostatic charge accumulates on the manufacture equipment, the display panel, the process practitioners, or somewhere else. During the manufacturing process, the ESD (Electrostatic Discharge) phenomenon occurs when the electronic ink display panel touches the manufacturer equipment, the process practitioners, or the substance carrying the static charge. Because the components of the electronic ink display device have very small size, the electrostatic discharge phenomenon will cause serious damage to the electronic ink display device. Taking the current electronic ink display device as the example, the electrostatic discharge phenomenon usually causes the abnormal displaying or the line defects on the display panel, such as the abnormal pixels in the external circuit outside the display area or the abnormal column/row pixels within the display area near the external matrix. This will decrease the manufacturing yield of the electronic ink display panel and the life cycle of the product.
FIG. 1A, and FIG. 1B show the cross sectional views of the conventional display device structures, in which the display device structure mainly includes the active region 111, the electrostatic protection circuit region 109, and the test circuit region 115. The first metal layer 103 and the second metal layer 105 are usually connected through the outermost third metal layer 101. However, during attaching the front plane laminate, the static electricity from the front plane laminate is easy to be transferred to the external circuit or other circuit through the third metal layer 101, which causes the short-circuit, and the panel defect or the abnormal displaying occurs. On the other hand, the potential of the data line or scan line located outside the display area causes the front panel laminate 107 to release the ions, and the ions with the water vapor form the chemicals that corrodes the insulating layer, thus the metal layer under the insulating layer is not protected. If the display device structure is exposed in the hot and humid environment, the water and the vapor will permeate therein and corrode the second metal layer 105 as well as the first metal layer 103, which causes the panel defects or the abnormal displaying.
Therefore, how to prevent the electrostatic discharge current from damaging the display device and how to improve the life cycle of the product have become an important issue for the electrophoretic display device.